JPS5916108A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To eliminate the disorder of connections, especially, for editing, by switching the recording state and the reproducing state without transient in a recording and reproducing device. CONSTITUTION:At the start time of editing, a recording circuit becomes conductive by the first signal 12, and the device is set to a state E-E from the reproducing state (at a point A). A recording amplifier 3 is made conductive by a signal 13 (at a point D), and actual recording is started by a signal 14 (at a point E). In this case, a signal 15 generates transient at the point D but is normal at the point E, and therefore, the signal 15 is recorded without distortion following a signal recorded already on a tape. At the end time of editing, signals 14, 13, and 12 are changed from the high level to the low level in order by a command, and transient is generated at a point G, but it is not flowed to a head, and therefore, signals are not dropped out, and pictures are not disordered.

Description

DETAILED DESCRIPTION OF THE INVENTION It is an object of the present invention to provide a recording and reproducing apparatus that can switch recording and reproducing states without transients, and in particular, can change transitions during editing: rt, kfi.

In a recording/reproducing device such as a VTR, as shown in Fig. 1, the head is switched during recording and playback, and the circuit for passing the recording current is switched, and the input signal or other signal is sent to the output terminal. Processed (FM modulated and demodulated) signal (
E-E system), but the head also reproduces a signal (V-
V system) is switched to output power. In Figure 1, 1 is an input signal terminal, 2 is a recording circuit, 3 is a recording amplifier, 4 is a head, 6 is a reproduction amplifier, 6 is a reproduction circuit, 7 is an output signal terminal, and 8 is a head selection switch (R: recording contact,
P: playback contact), 9 is recording amplifier cutoff switch, 10 is recording circuit cutoff switch, 11 [K''/v V switching switch f (E; E-E contact, V; v-■ contact), 12 is switch 1o and 11 is a control (goods) signal input terminal, 13 is a control (goods) signal input terminal of switch 9, and 14 is a control (goods) signal input terminal of switch 8.
This is the control signal input terminal. The video signal input to the input terminal 1 is processed by a recording circuit 2 such as FMK tone, amplified by a recording amplifier 3, and transferred to a magnetic tape (not shown) to a head 4 via an R contact of a head selector switch 8. ) recorded in n
Ru. Recording circuit cutoff switch 10fi is used to stop the oscillation of the FM modulation circuit in order to prevent interference with the FM signal during playback.The recorder amplifier cutoff switch 9 turns on the recording amplifier 3 during actual recording, and stops the oscillation of the FM modulation circuit during playback. Or, at E-8 when no recording is being performed, the recording amplifier 3 is cut off. Switches 1o and 9 cause circuit 2. When both recording amplifiers 30 are in a conductive state, the circuit for flowing the recording current is in a conductive state. E-8 o'clock,
The recording circuit 2 is made conductive by the switch 10, and its output FM
The signal is conducted to the reproducing circuit 6 via the E contact of the E-4/V-V changeover switch 11, modulates the input signal to the output terminal 7, and obtains a demodulated signal. During playback, the signal reproduced from the head 4 is amplified by the playback amplifier 5 through the head changeover switch 80P contact, and then guided to the playback circuit 6 through the V contact of the E-E/V-V changeover switch 11. Normally, the E-E mode is used when stopping or fast forwarding (FF) other than when actually recording.
L It is also often used when rewinding (REV).

Also, in order to check the input signal during playback, the player may temporarily enter the E-E mode to obtain the input signal from the output terminal.

This E-E/V-V switching 1-11. In response to a command from the VTR's operation button, a signal signal from terminal 12 is activated by switches 10 and 11. Actual recording, playback, stop, FF, and REV switching (controlling the signals at terminal 13 and terminal 14 from commands from the dVTH operation button, and is performed by switches 9 and 8.

The control signals for these terminals 13 and 14 are generated by the same command, so they are the same signal. During normal recording and playback switching, signal discontinuity, double writing, and deletions occur at the switching point.

However, in a VTR that performs editing, especially insert editing in which a certain part of an already recorded NFC video signal is replaced with another signal, it is important that the edited signals are continuous without any omission. The above-described switching between recording and playback causes the following inconvenience during insert editing. Fig. 2 shows the signal waveforms of each part of Fig. 1 in this case, and this inconvenience will be explained. In the figure, 12
, 13.14 show the control signal waveforms of the terminals 12, 13.14 in FIG. Sag
y (output signal 16 of the regenerative amplifier 5 when the signal is regenerated)
The waveform r is shown. At the start of editing, terminal 12 is connected by the first command.
The signal changes from a low level to a high level, the digital recording circuit 2 becomes conductive to the switch 10 in FIG.
Switching to the side, the sword becomes regenerated state > Gx-g state (point A in Figure 2). The next command causes the signals at terminals 13 and 14 to go from low level 711) to high level, switch 9 turns on recording amplifier 3, switch 8 goes to the R side, and actual recording starts (711). Point B in Figure 2). At this time, the output signal 16 of the recording amplifier 3 changes as shown at point B of the output signal 16 in FIG. 2 due to the transient of the switch 9. Also, when editing is finished, the signal at the input terminal 12+13114 changes from high level to low level in response to the command, the recording circuit 2 is cut off by the switch 10, the recording amplifier 3 is cut off by the switch 9, the switch 8 is switched to the P side, and the switch 8 is switched to the P side. 11 changes to the V side and enters the playback state again (point 0 in Figure 2). At this time signal 1
5, it changes like 0 point due to the transient of switch 9. The switching timing of the 11C1 control signals 13 and 14 varies somewhat depending on variations in the control signal generation circuit. FIG. 2 shows a case where the signal 14 is slightly slower than the signal 13. In such a case, signal 1
signal 14 goes low after 3 goes low 1
During this period, a downward transient pulse signal of signal 16 flows through the head, so that the signal already recorded on the tape is erased by this transient pulse. Therefore, when a tape subjected to insert editing in this manner is played back, the output signal 16 of the playback amplifier 5 becomes as shown in FIG. That is, at the start of editing, the recorded signal is distorted by a transient, the first part of the playback output becomes small, and at the end of editing, it is erased due to the transient, a non-recorded part is created, and the playback signal becomes noise, causing image disturbance. I'm in a trench.

To prevent this, the switch 9 should be made completely transient-free, but this would make the circuit complicated and expensive.

In view of the above points, we have decided to use a simple cut-off switch for the circuit for supplying the recording current, so that even if a transient occurs in the switch circuit, the recording state and playback state will remain unchanged. The resulting signal is continuous and eliminates image disturbance n.

FIG. 3 shows switching side leg signals for the recording state and playback state during insert editing according to the invention, and will be described. In Figure 3, 12, 13.14 are the terminals 12, 13.1 in Figure 1.
4 shows the control signal waveform, and 15 shows the waveform of the output signal 16 of the recording amplifier 3 in FIG. The waveform of the output signal 16 is shown.

At the start of editing, signal 12 is set to low level 7) due to the first command.
) changes to a high level, the recording circuit 2 is turned on by the switch 10 in FIG. 1, the switch 11 changes to the E side, and the reproduction state changes to the E-E state (point A in FIG. 3). In response to the next command, the signal 13 changes from a low level to a high level, and the switch 9 turns on the recording amplifier 3 (the third
point D in the figure). After a delay n, the signal 14 changes from a low level to a high level, the switch 8 is turned to the R side, and actual recording begins (point E in FIG. 3). At this time, the signal 15 becomes as shown in the figure, and although a transient occurs at point D, it is normal at point E, so that it is recorded continuously on the signal already recorded on the tape without distortion. Also, when editing is finished, the command first changes the signal 14 from high level to low level, changes the switch 8 to the P side, and ends the recording (
point F). Next, after a delay, the signal 13 changes from a high level to a low level, and the recording amplifier 3 is cut off by the switch 9 (point G). That is, the circuit for passing the recording current is cut off. Further later than this, the signal 12 changes from a high level to a low level, the recording circuit 2 is cut off by the switch 1o, and the switch 11 is turned to the V side to enter the V-■ mode (H
point). At this time, a transient occurs in the signal 16 at point G at point 9 in the figure, but since the switch 8 has already changed to the P side at point F, the signal does not flow to the head of the transient 14J, and the signal is recorded on the tape. The newly recorded signal and the previously recorded signal become continuous without being erased.

When the insert-edited signal is reproduced in this manner, the output signal 16 of the reproduction amplifier 5 is connected continuously as shown in FIG. 3, and there is no signal loss and no image disturbance. In this way, the present invention requires only one use to set the head in the recording mode (R).
The circuit for causing the recording current to flow is cut off later than when the head is switched from the playback mode (point F) to the playback mode (point Make the circuit fully conductive for the current current “j” (D
By doing so, it is possible to switch between the recording state and the playback state without any transient, and to eliminate the disturbance of transitions during editing. Note that the state in which the circuit for passing the recording current is cut off means that both the recording circuit 2 and the recording amplifier 3 are cut off. In the above description, signals 12, 13, . J: It was assumed that the level reached a high level quickly and decreased to a low level later.
Even if this n is reversed, both signals 12 and 13 are connected to signal 14.
A similar effect can be obtained if the processed signal 15 becomes high enough early enough for the transient to subside and becomes low level late enough. In addition, in the above example, switches 10 and 11γ
Although the same control signal 12 was used for control, separate signals may be used. At this time, it is necessary to make the high level period of the control signal of the switch 10 longer than the high level period of the control signal of the switch 11. In this case, if you cut off the circuit for flowing the recording current or set the E-E/V-V changeover switch 11' to the 4v-v side, the playback signal will not receive interference due to the recording signal. ) k occurs, so the switch 11 should be switched to the V-V side at the same time as cutting off the circuit for causing the recording current to flow, or at the same time as the switch 11. When the configuration for turning off the power to the regenerative amplifier 5 is adopted, it takes some time to turn on the power to the regenerative amplifier 5 from the moment the signal 14 changes to a low level. During this period, the switch 11i"J:E-E side (Signal 1
2 is at a high level), and after the regenerative amplifier 6 has sufficiently started up, the switch 112 is switched to the V-V side, thereby eliminating the lack of output signal and the disturbance at the end of editing. 1st
In the illustrated example, the input signal is FM-modulated and then fully demodulated as the E-E signal, but the input signal may be switched to a reproduction signal immediately before the output terminal 7.

The above has described the case of the Keinsart editing of the present invention, but the inventive method has exactly the same effect in the case of assemble editing in which another signal is continuously recorded following the recorded signal, or in the case of simple splicing. It is something.

Next, the waveforms of a specific example of the method for creating the control signals 12, 13, and 14 shown in FIG. 3 are shown in FIG. 4 and will be explained together with the waveform diagram of FIG. 2 and the block diagram of FIG. 1.

In FIG. 4, 12, 13, and 14 represent the same signals as in FIG. 17 is a first editing command signal, 18 is an editing start command signal, 19 is a framing signal, and 20 is a rotary erase circuit side signal.

Signal 19 indicates an odd number field when it is high level, and an even number field 7 when it is low level.

Vertical blanking at the falling point. Switching during VTR editing is performed during vertical blanking. Also, since the video signal is recorded and played back using a rotating head, it is difficult to use the full-width erase head during insert editing to erase only the portion of the video signal that you want to replace. This is performed by a rotary erase head mounted within the same rotation radius as the head. Therefore, the erasing current is passed through the rotary erase head in advance of the insertion period of the video signal by the amount preceding the rotary erase head.

Currently, the rotary erase head is 1/2 times larger than the video head.
Assume that the two fields are installed in advance. 1st edit command 17 given nfl (became high level)
At this time (point A), the signal 12 becomes high level, the switches 10 and 11 in FIG. Next, when the editing start command 18 is given (becomes high level) (1 point), the rotary erase circuit starts at the midpoint (point D) between the falling and rising edges of the next framing signal 19 at that point. The side signal 20 becomes high level and the rotary erase current flows. At this □ time, the signal 13 becomes high level at the same time, and the switch 9 in Fig.
p recording amplifier 3 becomes conductive. Next, when the signal +f20 becomes high level (point D), the rising point of the next signal 19 (
At point E (within vertical blanking), the signal 14 becomes high level, and the switch 8 is turned to the R side, allowing current to flow through the head 4. At this time, the video head was attached to the rotary erase head in advance of the 1/2 field.
The rotary erase current also flows 1/2 field ahead of the recording current, so the video signal input is just right.
The part to be replaced will be deleted. Also, since the signal 13 becomes high level 1/2 field earlier than the signal 14, the transient of the signal 15 is reduced during this period. At the end of editing, both the first editing command signal 17 and the editing start signal 18 become low level (5 points). At the midpoint (point K) between the falling and rising edges of the next signal 19 at this point, the rotary erase circuit control signal 2o becomes low level, and erasing is stopped. At the rising point of the signal 19 next to this point (point F, within the vertical blanking), the signal 14 becomes low level and the switch 8 is turned to the P side, and recording stops. At this time, only the portion where the video signals are replaced is erased. Furthermore,
The next fall of signal 19 after point F is point A (point G), and signal 13 becomes low level.
cut off.

Furthermore, the rising point of signal 19 next to this point G (point H)
When the signal 12 is at a low level, the switches 10 and 11 are switched to I) v-v mode. This circuit can be easily realized by using a D-type flip-flop 07 that uses a signal 19 as a clock.

In addition, in the explanation of FIG. 4, the falling point of signal 13 is used as the falling point of signal 19, but since it takes only a short time for signal 13 to fall from point F to 9, it falls at point F. It is sufficient to integrate the entire signal, shape it, and delay it to create the falling point of the signal 13. The fall of the reed signal 12 may be the same as or later than the fall of the signal 13, and may be after the time when the regenerative amplifier 6 reaches a steady state.

Although the invention has been described above regarding switching between recording and reproduction of video signals, the invention can also be applied to switching between recording and reproduction of not only video signals but also audio signals and other signals.

As described above, if the present invention is applied, even if a simple switch circuit that causes a transient in the circuit for flowing the recording current is used, the transient force < switching between the recording state and the playback state, and the switching during editing. Signal loss or disturbance nAr:1< can occur.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a recording/reproducing switching circuit that switches between a recording state and a reproducing state in a recording/reproducing apparatus. FIG. 2 is a conventional signal waveform diagram of each part of the recording/reproducing switching circuit. FIG. 4 is a signal waveform diagram of each part of an embodiment of the recording/reproduction switching circuit according to the invention. FIG. 4 is a diagram of signal waveforms of each part of an embodiment of the control signal generation circuit of FIG. 4...Head, 8,9.101 11...
・・Switch, 12p 13+ 14・・・・・・
Switch control signal. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 8p Snake E to H

Claims (1)

[Claims] (1) The circuit for passing the recording current is cut off later than the switching of the head from recording mode to the playback mode, and the circuit for passing the recording current is cut off faster than the switching of the head from the playback mode to the recording mode. A recording/reproducing device characterized by electrical conduction. After cutting off the recording current to the head, the signal led to the output terminal is transferred to the input signal to be recorded or f'
2. The recording/reproducing apparatus according to claim 1, wherein the recording/reproducing apparatus switches from a signal power obtained by processing L to a reproduction signal.